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gdb
gdb-orphanripper.c
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File gdb-orphanripper.c of Package gdb
/* * Copyright 2006-2007 Free Software Foundation, Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * Reap any leftover children possibly holding file descriptors. * Children are identified by the stale file descriptor or PGID / SID. * Both can be missed but only the stale file descriptors are important for us. * PGID / SID may be set by the children on their own. * If we fine a candidate we kill it will all its process tree (grandchildren). * The child process is run with `2>&1' redirection (due to forkpty(3)). * 2007-07-10 Jan Kratochvil <jan.kratochvil@redhat.com> */ /* For getpgid(2). */ #define _GNU_SOURCE 1 #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/wait.h> #include <dirent.h> #include <unistd.h> #include <errno.h> #include <ctype.h> #include <string.h> #include <limits.h> #include <fcntl.h> #include <assert.h> #include <pty.h> #include <poll.h> #include <sys/stat.h> #define LENGTH(x) (sizeof (x) / sizeof (*(x))) static const char *progname; static volatile pid_t child; static void signal_chld (int signo) { } static volatile int signal_alrm_hit = 0; static void signal_alrm (int signo) { signal_alrm_hit = 1; } static char childptyname[LINE_MAX]; static void print_child_error (const char *reason, char **argv) { char **sp; fprintf (stderr, "%s: %d %s:", progname, (int) child, reason); for (sp = argv; *sp != NULL; sp++) { fputc (' ', stderr); fputs (*sp, stderr); } fputc ('\n', stderr); } static int read_out (int amaster) { char buf[LINE_MAX]; ssize_t buf_got; buf_got = read (amaster, buf, sizeof buf); if (buf_got == 0) return 0; /* Weird but at least after POLLHUP we get EIO instead of just EOF. */ if (buf_got == -1 && errno == EIO) return 0; if (buf_got == -1 && errno == EAGAIN) return 0; if (buf_got < 0) { perror ("read (amaster)"); exit (EXIT_FAILURE); } if (write (STDOUT_FILENO, buf, buf_got) != buf_got) { perror ("write(2)"); exit (EXIT_FAILURE); } return 1; } /* kill (child, 0) == 0 sometimes even when CHILD's state is already "Z". */ static int child_exited (void) { char buf[200]; int fd, i, retval; ssize_t got; char state[3]; snprintf (buf, sizeof (buf), "/proc/%ld/stat", (long) child); fd = open (buf, O_RDONLY); if (fd == -1) { perror ("open (/proc/CHILD/stat)"); exit (EXIT_FAILURE); } got = read (fd, buf, sizeof(buf)); if (got <= 0) { perror ("read (/proc/CHILD/stat)"); exit (EXIT_FAILURE); } if (close (fd) != 0) { perror ("close (/proc/CHILD/stat)"); exit (EXIT_FAILURE); } /* RHEL-5 does not support %ms. */ i = sscanf (buf, "%*d%*s%2s", state); if (i != 1) { perror ("sscanf (/proc/CHILD/stat)"); exit (EXIT_FAILURE); } retval = strcmp (state, "Z") == 0; return retval; } static int spawn (char **argv, int timeout) { pid_t child_got; int status, amaster, i, rc; struct sigaction act; sigset_t set; struct termios termios; unsigned alarm_orig; /* We do not use signal(2) to be sure we do not have SA_RESTART. */ memset (&act, 0, sizeof (act)); act.sa_handler = signal_chld; i = sigemptyset (&act.sa_mask); assert (i == 0); act.sa_flags = 0; /* !SA_RESTART */ i = sigaction (SIGCHLD, &act, NULL); assert (i == 0); i = sigemptyset (&set); assert (i == 0); i = sigaddset (&set, SIGCHLD); assert (i == 0); i = sigprocmask (SIG_SETMASK, &set, NULL); assert (i == 0); /* With TERMP passed as NULL we get "\n" -> "\r\n". */ termios.c_iflag = IGNBRK | IGNPAR; termios.c_oflag = 0; termios.c_cflag = CS8 | CREAD | CLOCAL | HUPCL | B9600; termios.c_lflag = IEXTEN | NOFLSH; memset (termios.c_cc, _POSIX_VDISABLE, sizeof (termios.c_cc)); termios.c_cc[VTIME] = 0; termios.c_cc[VMIN ] = 1; cfmakeraw (&termios); #ifdef FLUSHO /* Workaround a readline deadlock bug in _get_tty_settings(). */ termios.c_lflag &= ~FLUSHO; #endif child = forkpty (&amaster, childptyname, &termios, NULL); switch (child) { case -1: perror ("forkpty(3)"); exit (EXIT_FAILURE); case 0: /* Do not replace STDIN as inferiors query its termios. */ #if 0 i = close (STDIN_FILENO); assert (i == 0); i = open ("/dev/null", O_RDONLY); assert (i == STDIN_FILENO); #endif i = sigemptyset (&set); assert (i == 0); i = sigprocmask (SIG_SETMASK, &set, NULL); assert (i == 0); /* Do not setpgrp(2) in the parent process as the process-group is shared for the whole sh(1) pipeline we could be a part of. The process-group is set according to PID of the first command in the pipeline. We would rip even vi(1) in the case of: ./orphanripper sh -c 'sleep 1&' | vi - */ /* Do not setpgrp(2) as our pty would not be ours and we would get `SIGSTOP' later, particularly after spawning gdb(1). setsid(3) was already executed by forkpty(3) and it would fail if executed again. */ if (getpid() != getpgrp ()) { perror ("getpgrp(2)"); exit (EXIT_FAILURE); } execvp (argv[0], argv); perror ("execvp(2)"); exit (EXIT_FAILURE); default: break; } i = fcntl (amaster, F_SETFL, O_RDWR | O_NONBLOCK); if (i != 0) { perror ("fcntl (amaster, F_SETFL, O_NONBLOCK)"); exit (EXIT_FAILURE); } /* We do not use signal(2) to be sure we do not have SA_RESTART. */ act.sa_handler = signal_alrm; i = sigaction (SIGALRM, &act, NULL); assert (i == 0); alarm_orig = alarm (timeout); assert (alarm_orig == 0); i = sigemptyset (&set); assert (i == 0); while (!signal_alrm_hit) { struct pollfd pollfd; pollfd.fd = amaster; pollfd.events = POLLIN; i = ppoll (&pollfd, 1, NULL, &set); if (i == -1 && errno == EINTR) { if (child_exited ()) break; /* Non-CHILD child may have exited. */ continue; } assert (i == 1); /* Data available? Process it first. */ if (pollfd.revents & POLLIN) { if (!read_out (amaster)) { fprintf (stderr, "%s: Unexpected EOF\n", progname); exit (EXIT_FAILURE); } } if (pollfd.revents & POLLHUP) break; if ((pollfd.revents &= ~POLLIN) != 0) { fprintf (stderr, "%s: ppoll(2): revents 0x%x\n", progname, (unsigned) pollfd.revents); exit (EXIT_FAILURE); } /* Child exited? */ if (child_exited ()) break; } if (signal_alrm_hit) { i = kill (child, SIGKILL); assert (i == 0); } else alarm (0); /* WNOHANG still could fail. */ child_got = waitpid (child, &status, 0); if (child != child_got) { fprintf (stderr, "waitpid (%d) = %d: %m\n", (int) child, (int) child_got); exit (EXIT_FAILURE); } if (signal_alrm_hit) { char *buf; if (asprintf (&buf, "Timed out after %d seconds", timeout) != -1) { print_child_error (buf, argv); free (buf); } rc = 128 + SIGALRM; } else if (WIFEXITED (status)) rc = WEXITSTATUS (status); else if (WIFSIGNALED (status)) { print_child_error (strsignal (WTERMSIG (status)), argv); rc = 128 + WTERMSIG (status); } else if (WIFSTOPPED (status)) { fprintf (stderr, "waitpid (%d): WIFSTOPPED - WSTOPSIG is %d\n", (int) child, WSTOPSIG (status)); exit (EXIT_FAILURE); } else { fprintf (stderr, "waitpid (%d): !WIFEXITED (%d)\n", (int) child, status); exit (EXIT_FAILURE); } /* Not used in fact. */ i = sigprocmask (SIG_SETMASK, &set, NULL); assert (i == 0); /* Do not unset O_NONBLOCK as a stale child (the whole purpose of this program) having open its output pty would block us in read_out. */ #if 0 i = fcntl (amaster, F_SETFL, O_RDONLY /* !O_NONBLOCK */); if (i != 0) { perror ("fcntl (amaster, F_SETFL, O_RDONLY /* !O_NONBLOCK */)"); exit (EXIT_FAILURE); } #endif while (read_out (amaster)); /* Do not close the master FD as the child would have `/dev/pts/23 (deleted)' entries which are not expected (and expecting ` (deleted)' would be a race. */ #if 0 i = close (amaster); if (i != 0) { perror ("close (forkpty ()'s amaster)"); exit (EXIT_FAILURE); } #endif return rc; } /* Detected commandline may look weird due to a race: Original command: ./orphanripper sh -c 'sleep 1&' & Correct output: [1] 29610 ./orphanripper: Killed -9 orphan PID 29612 (PGID 29611): sleep 1 Raced output (sh(1) child still did not update its argv[]): [1] 29613 ./orphanripper: Killed -9 orphan PID 29615 (PGID 29614): sh -c sleep 1& We could delay a bit before ripping the children. */ static const char *read_cmdline (pid_t pid) { char cmdline_fname[32]; static char cmdline[LINE_MAX]; int fd; ssize_t got; char *s; if (snprintf (cmdline_fname, sizeof cmdline_fname, "/proc/%d/cmdline", (int) pid) < 0) return NULL; fd = open (cmdline_fname, O_RDONLY); if (fd == -1) { /* It may have already exited - ENOENT. */ #if 0 fprintf (stderr, "%s: open (\"%s\"): %m\n", progname, cmdline_fname); #endif return NULL; } got = read (fd, cmdline, sizeof (cmdline) - 1); if (got == -1) fprintf (stderr, "%s: read (\"%s\"): %m\n", progname, cmdline_fname); if (close (fd) != 0) fprintf (stderr, "%s: close (\"%s\"): %m\n", progname, cmdline_fname); if (got < 0) return NULL; /* Convert '\0' argument delimiters to spaces. */ for (s = cmdline; s < cmdline + got; s++) if (!*s) *s = ' '; /* Trim the trailing spaces (typically single '\0'->' '). */ while (s > cmdline && isspace (s[-1])) s--; *s = 0; return cmdline; } static int dir_scan (const char *dirname, int (*callback) (struct dirent *dirent, const char *pathname)) { DIR *dir; struct dirent *dirent; int rc = 0; dir = opendir (dirname); if (dir == NULL) { if (errno == EACCES || errno == ENOENT) return rc; fprintf (stderr, "%s: opendir (\"%s\"): %m\n", progname, dirname); exit (EXIT_FAILURE); } while ((errno = 0, dirent = readdir (dir))) { char pathname[LINE_MAX]; int pathname_len; pathname_len = snprintf (pathname, sizeof pathname, "%s/%s", dirname, dirent->d_name); if (pathname_len <= 0 || pathname_len >= (int) sizeof pathname) { fprintf (stderr, "entry file name too long: `%s' / `%s'\n", dirname, dirent->d_name); continue; } /* RHEL-4.5 on s390x never fills in D_TYPE. */ if (dirent->d_type == DT_UNKNOWN) { struct stat statbuf; int i; /* We are not interested in the /proc/PID/fd/ links targets. */ i = lstat (pathname, &statbuf); if (i == -1) { if (errno == EACCES || errno == ENOENT) continue; fprintf (stderr, "%s: stat (\"%s\"): %m\n", progname, pathname); exit (EXIT_FAILURE); } if (S_ISDIR (statbuf.st_mode)) dirent->d_type = DT_DIR; if (S_ISLNK (statbuf.st_mode)) dirent->d_type = DT_LNK; /* No other D_TYPE types used in this code. */ } rc = (*callback) (dirent, pathname); if (rc != 0) { errno = 0; break; } } if (errno != 0) { fprintf (stderr, "%s: readdir (\"%s\"): %m\n", progname, dirname); exit (EXIT_FAILURE); } if (closedir (dir) != 0) { fprintf (stderr, "%s: closedir (\"%s\"): %m\n", progname, dirname); exit (EXIT_FAILURE); } return rc; } static int fd_fs_scan (pid_t pid, int (*func) (pid_t pid, const char *link)) { char dirname[64]; if (snprintf (dirname, sizeof dirname, "/proc/%d/fd", (int) pid) < 0) { perror ("snprintf(3)"); exit (EXIT_FAILURE); } int callback (struct dirent *dirent, const char *pathname) { char buf[LINE_MAX]; ssize_t buf_len; if ((dirent->d_type != DT_DIR && dirent->d_type != DT_LNK) || (dirent->d_type == DT_DIR && strcmp (dirent->d_name, ".") != 0 && strcmp (dirent->d_name, "..") != 0) || (dirent->d_type == DT_LNK && strspn (dirent->d_name, "0123456789") != strlen (dirent->d_name))) { fprintf (stderr, "Unexpected entry \"%s\" (d_type %u)" " on readdir (\"%s\"): %m\n", dirent->d_name, (unsigned) dirent->d_type, dirname); return 0; } if (dirent->d_type == DT_DIR) return 0; buf_len = readlink (pathname, buf, sizeof buf - 1); if (buf_len <= 0 || buf_len >= (ssize_t) sizeof buf - 1) { if (errno != ENOENT && errno != EACCES) fprintf (stderr, "Error reading link \"%s\": %m\n", pathname); return 0; } buf[buf_len] = 0; return (*func) (pid, buf); } return dir_scan (dirname, callback); } static void pid_fs_scan (void (*func) (pid_t pid, void *data), void *data) { int callback (struct dirent *dirent, const char *pathname) { if (dirent->d_type != DT_DIR || strspn (dirent->d_name, "0123456789") != strlen (dirent->d_name)) return 0; (*func) (atoi (dirent->d_name), data); return 0; } dir_scan ("/proc", callback); } static int rip_check_ptyname (pid_t pid, const char *link) { assert (pid != getpid ()); return strcmp (link, childptyname) == 0; } struct pid { struct pid *next; pid_t pid; }; static struct pid *pid_list; static int pid_found (pid_t pid) { struct pid *entry; for (entry = pid_list; entry != NULL; entry = entry->next) if (entry->pid == pid) return 1; return 0; } /* Single pass is not enough, a (multithreaded) process was seen to survive. Repeated killing of the same process is not enough, zombies can be killed. */ static int cleanup_acted; static void pid_record (pid_t pid) { struct pid *entry; if (pid_found (pid)) return; cleanup_acted = 1; entry = malloc (sizeof (*entry)); if (entry == NULL) { fprintf (stderr, "%s: malloc: %m\n", progname); exit (EXIT_FAILURE); } entry->pid = pid; entry->next = pid_list; pid_list = entry; } static void pid_forall (void (*func) (pid_t pid)) { struct pid *entry; for (entry = pid_list; entry != NULL; entry = entry->next) (*func) (entry->pid); } /* Returns 0 on failure. */ static pid_t pid_get_parent (pid_t pid) { char fname[64]; FILE *f; char line[LINE_MAX]; pid_t retval = 0; if (snprintf (fname, sizeof fname, "/proc/%d/status", (int) pid) < 0) { perror ("snprintf(3)"); exit (EXIT_FAILURE); } f = fopen (fname, "r"); if (f == NULL) { return 0; } while (errno = 0, fgets (line, sizeof line, f) == line) { if (strncmp (line, "PPid:\t", sizeof "PPid:\t" - 1) != 0) continue; retval = atoi (line + sizeof "PPid:\t" - 1); errno = 0; break; } if (errno != 0) { fprintf (stderr, "%s: fgets (\"%s\"): %m\n", progname, fname); exit (EXIT_FAILURE); } if (fclose (f) != 0) { fprintf (stderr, "%s: fclose (\"%s\"): %m\n", progname, fname); exit (EXIT_FAILURE); } return retval; } static void killtree (pid_t pid); static void killtree_pid_fs_scan (pid_t pid, void *data) { pid_t parent_pid = *(pid_t *) data; /* Do not optimize it as we could miss some newly spawned processes. Always traverse all the leaves. */ #if 0 /* Optimization. */ if (pid_found (pid)) return; #endif if (pid_get_parent (pid) != parent_pid) return; killtree (pid); } static void killtree (pid_t pid) { pid_record (pid); pid_fs_scan (killtree_pid_fs_scan, &pid); } static void rip_pid_fs_scan (pid_t pid, void *data) { pid_t pgid; /* Shouldn't happen. */ if (pid == getpid ()) return; /* Check both PGID and the stale file descriptors. */ pgid = getpgid (pid); if (pgid == child || fd_fs_scan (pid, rip_check_ptyname) != 0) killtree (pid); } static void killproc (pid_t pid) { const char *cmdline; cmdline = read_cmdline (pid); /* Avoid printing the message for already gone processes. */ if (kill (pid, 0) != 0 && errno == ESRCH) return; if (cmdline == NULL) cmdline = "<error>"; fprintf (stderr, "%s: Killed -9 orphan PID %d: %s\n", progname, (int) pid, cmdline); if (kill (pid, SIGKILL) == 0) cleanup_acted = 1; else if (errno != ESRCH) fprintf (stderr, "%s: kill (%d, SIGKILL): %m\n", progname, (int) pid); /* RHEL-3 kernels cannot SIGKILL a `T (stopped)' process. */ kill (pid, SIGCONT); /* Do not waitpid(2) as it cannot be our direct descendant and it gets cleaned up by init(8). */ #if 0 pid_t pid_got; pid_got = waitpid (pid, NULL, 0); if (pid != pid_got) { fprintf (stderr, "%s: waitpid (%d) != %d: %m\n", progname, (int) pid, (int) pid_got); return; } #endif } static void rip (void) { cleanup_acted = 0; do { if (cleanup_acted) usleep (1000000 / 10); cleanup_acted = 0; pid_fs_scan (rip_pid_fs_scan, NULL); pid_forall (killproc); } while (cleanup_acted); } int main (int argc, char **argv) { int timeout = 0; int rc; progname = *argv++; argc--; if (argc < 1 || strcmp (*argv, "-h") == 0 || strcmp (*argv, "--help") == 0) { puts ("Syntax: orphanripper [-t <seconds>] <execvp(3) commandline>"); exit (EXIT_FAILURE); } if ((*argv)[0] == '-' && (*argv)[1] == 't') { char *timeout_s = NULL; if ((*argv)[2] == 0) timeout_s = *++argv; else if (isdigit ((*argv)[2])) timeout_s = (*argv) + 2; if (timeout_s != NULL) { long l; char *endptr; argv++; l = strtol (timeout_s, &endptr, 0); timeout = l; if ((endptr != NULL && *endptr != 0) || timeout < 0 || timeout != l) { fprintf (stderr, "%s: Invalid timeout value: %s\n", progname, timeout_s); exit (EXIT_FAILURE); } } } rc = spawn (argv, timeout); rip (); return rc; }
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